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Looking to go 10K. Dual or single coil?

J

jtaggie320

Guest
Ok guys, I finally got my head outa my butt w/ the firestiks and wilson fiberglass antennas and im looking to go w/ a 10K. My question is does it really make a damn bit of difference in whether i go w/ single or double coils? I know it affects the overall height but does it ever affect the performance?
 

Yes, I had heard that the single had an advantage but i had never seen any tests to prove it. Hmmm, I just figured that since being physically taller is always an advantage in antennas then the single would perform better than the double coil.
 
"Single coil! Why? Because Justin did some real world tests and the single coil was better than the dual coil. Why? I don't know."

something happens that doesn't occur in the single coil model. at an instant in time (degrees) the phase angle of the signal (voltage and current) is quickly and abruptly "shifted" between the top of the bottom inductor and the bottom of the top inductor in such a way that power is lost to (converted into) heat. the inherent and obvious result is loss of radiation efficiency. the area in between the two inductors represents a hump of sorts in that the fluid geometry of the inductor is disturbed as are also values of E and I, resulting in the above phenomenon.

i'd like to hear any other takes on this.
 
freecell said:
"Single coil! Why? Because Justin did some real world tests and the single coil was better than the dual coil. Why? I don't know."

something happens that doesn't occur in the single coil model. at an instant in time (degrees) the phase angle of the signal (voltage and current) is quickly and abruptly "shifted" between the top of the bottom inductor and the bottom of the top inductor in such a way that power is lost to (converted into) heat. the inherent and obvious result is loss of radiation efficiency. the area in between the two inductors represents a hump of sorts in that the fluid geometry of the inductor is disturbed as are also values of E and I, resulting in the above phenomenon.

i'd like to hear any other takes on this.
Click to expand...
RF likes the shortest path. The single coil will be the shortest. Kale
 
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"RF likes the shortest path."

bullshit. impedance is the total opposition to current flow in an ac circuit, consisting of both resistance and reactance. rf takes the path presenting the least value of impedance. if two "paths" are present, a physically short path with thousands of ohms of impedance present and a longer physical path with an extremely low impedance the rf will follow the physically longer path.

"The single coil will be the shortest."

irrelevant. the gap between the inductors in the dual coil creates an unnecessary impedance bump while the single coil smoothly transitions the current and voltage values without any abrupt changes. Z=E/I. appearance sells more of these dual coil antennas than does performance, that's why (one of several reasons) when they're replaced with multi-element top loaded antennas performance is literally doubled and in some cases tripled in terms of actual distances covered.
 
freecell said:
"RF likes the shortest path."

bullshit. impedance is the total opposition to current flow in an ac circuit, consisting of both resistance and reactance. rf takes the path presenting the least value of impedance. if two "paths" are present, a physically short path with thousands of ohms of impedance present and a longer physical path with an extremely low impedance the rf will follow the physically longer path.

"The single coil will be the shortest."

irrelevant. the gap between the inductors in the dual coil creates an unnecessary impedance bump while the single coil smoothly transitions the current and voltage values without any abrupt changes. Z=E/I. appearance sells more of these dual coil antennas than does performance, that's why (one of several reasons) when they're replaced with multi-element top loaded antennas performance is literally doubled and in some cases tripled in terms of actual distances covered.
Click to expand...
Why does a stick out perform coil antennas if this is true. I don't build antennas for appearance, I build them to perform. Apperance takes care of itself. The only reason for the added coil is to shorten the overall length, impedance bump or not.
What I meant was the shorter antenna(in electrical inches) will have very little reactance if none at all which will make a little bit better performer than the longer antenna. Kale
 
"The only reason for the added coil is to shorten the overall length........"

your single coil outperforms the dual coil. if you want to physically shorten the single coil further, use a longer coil or a larger diameter coil instead of breaking it up into two sections. this only degrades the radiation efficiency.

"will have very little reactance if none at all which will make a little bit better performer........"

you have no idea what you're talking about. every antenna possesses the property of reactance. if they didn't they couldn't radiate a signal. the only time an antenna has "zero" reactance is when both (positive values of) inductive and capacitive reactances are of equal amounts and thus cancel each other out. this condition of an antenna is referred to as "resonance." there's no such thing as an antenna with NO reactance.
 
freecell said:
"The only reason for the added coil is to shorten the overall length........"

your single coil outperforms the dual coil. if you want to physically shorten the single coil further, use a longer coil or a larger diameter coil instead of breaking it up into two sections. this only degrades the radiation efficiency.

"will have very little reactance if none at all which will make a little bit better performer........"

you have no idea what you're talking about. every antenna possesses the property of reactance. if they didn't they couldn't radiate a signal. the only time an antenna has "zero" reactance is when both (positive values of) inductive and capacitive reactances are of equal amounts and thus cancel each other out. this condition of an antenna is referred to as "resonance." there's no such thing as an antenna with NO reactance.
Click to expand...
There's no sutch thing as a "resonant "antenna "with" reactance. Do you not know what a damn Bird meter is? It's one of the best meters to tune an antenna to show how much reactance the antenna has. Any antenna that has a high reactance isn't going to perform very well. That's what tears up computer systems in vehicles is from a piss poor antenna system with a lot of reflect. I tried the longer coil thing you was talking about 10 years ago and found out that the longer coil showed more reflect than by breaking it up into two coils in the 10K antennas. I don't know about any other antennas and really don't care. I wrote the book on 10K antennas and that's all I care about.

You've done nothing but run down a fairly good product and criticize me and tell me that I don't know what I am talking about. Your track record shows that you're this way on every subject you comment on. Sounds like you have memorized a few facts out of some books somewhere. What do you have to go with it? What product do you manufacture? Maybe I should make some changes in my antenna design to be like you say and then maybe it would be one of the top of the line sntennas.Kale
 
"There's no sutch thing as a "resonant "antenna "with" reactance."
"Do you not know what a damn Bird meter is?"
"It's one of the best meters ...................to show how much reactance the antenna has."

oh really? and when was that feature added?

every antenna has reactance whether it's resonant or not and a bird meter doesn't measure reactance, it measures forward and reflected power using a nomograph with which to calculate swr. the antenna can produce zero reflected power and still be resonant far away from the frequency where reflected power = 0. those measurements can only be made with a GDM, a noise bridge or an analyzer. in a non resonant antenna (frequency dependent) the amounts of capacitive and inductive reactance are not equal, in a resonant antenna these values are equal and cancel so that X = 0. if you are able to measure the amounts of each it's a simple subtraction formula.

i haven't "run down" anything. take another look at the topic title. if you were referring to my comments Posted: Sat Aug 12, 2006 9:22 in connection with the remarks concerning the top loaded antennas, i was simply stating the facts.
 
What it amounts to is that coils have 'internal' losses. The bigger the coil (no matter if it's a single coil or a bunch of them) the bigger the losses. The only reason (good one, any way) is to 'shorten' an otherwise 'too long' antenna. That's it, period. Just how much is that shortening worth to you? Beats me, but that's what it amounts too. One large coil or several smaller ones, doesn't really make that much difference, besides 'looks'. Like the looks of some particular antenna? Fine, have at it! Want the 'best' radiation pattern? Use the 'full length' version of whatever electrical length you want, it'll out perform the shorter version. Lots of "if's", or "buts" in that but generally true. Then again, a four foot antenna is a lot easier to 'live' with than a 9 foot antenna. Take your pick, it's your choice..
- 'Doc
 
there's no such thing as an antenna with NO reactance.

"Your track record shows that you're this way on every subject you comment on. Sounds like you have memorized a few facts out of some books somewhere. What do you have to go with it?"

you have a computer there conected to the world wide internet, do you know how to use it?

and my "track record" shows that i'm "what way" exacty? if it shows anything it demonstrates that i know what i'm talking about, particularly to anyone who has spent any time or money educating themselves and confirming the veracity of my statements.
 

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